import React, { Component } from 'react'

export default class About extends Component {
    constructor(){
        super();
        this.state={
            arr:[1,2,3,4],
            arr2:[{id:1},{id:2},{id:3},{id:4}]
        }
    }
  render() {
    let newarr = this.state.arr2.map(item=><div key={item.id}><button>{item.id}</button></div>)
    return (
        <React.Fragment>
            <div>
                {this.state.arr}
               {newarr}
            </div>
        </React.Fragment>
    )
  }
}
